Metal cast electric motor



y 31, 195.1 M. a. SAWYER, SR 2,562,283

METAL CAST ELECTRIC MOTOR Filed Feb. 11, 1946 2 Sheets-Sheet 1 [hr en o Marion .5? fiazayegjzt llr'arner July 31, 19 1' M. B. SAWYER, SR

METAL CAST ELECTRIC MOTOR Filed Feb. 11, 1946 2 Sheets-Sheet 2 Fig. 2

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Patented July 31, 1951 METAL CAST ELECTRIC MOTOR Marion 3. Sawyer, Sr., Whittier, Calm, asslgnor to A. 0. Smith Electrical Mfg. 60., Los Angeles, Calif, a corporation of California Application February 11, 1946, Serial No. 646,749

' 2 Claims. (01.172-120) This invention relates to a metal cast electric motor or other dynamo electric element and has particular reference to protecting the windings of the stator of a squirrel cage induction motor from oil, moisture or the like by casting a soft non-magnetic metal, such as solder around the laminations and windings to seal oil the same and provide a solid protective coverin therefor.

The principal object of the invention i to provide an electric motor element in which the windings are free from attack by oil or liquids in which the motor is operated.

Another object is to provide a covering for motor windings in which heat conduction is very eillcient.

Another object is to provide a perfect seal against fluid leakage to the windings of a motor.

A further object is to provide a method of casting a solid metal protective covering around motor windings.

These and other objects of the invention will appear hereinafter in connection with the following description of an embodiment of the invention illustrated in the accompanying drawings.

In the drawing:

Figure 1 i a vertical sectional view of a stator held in a jig and after the pouring of th cast metal and location in the oven;

Fig. 2 is an enlarged detail section taken on line 2-2 of Fi ure 1; and

Fig. 3 is a fragmentary view of a stator completed in accordance with the invention under which the cast metal is bored out to the nonmagnetic tube.

The drawings illustrate a stator I comprising a plurality of laminations 2 stacked together and having longitudinal slots 3 in which are disposed windings I with the end coils 5 of the windings extending outwardly from each end of the stacked laminations.

The mouth of each slot 2 is closed by a slot stick 6 of glass board or the like and a thin strip 1 of non-magnetic material. The slot stick 6 generally a eutectic of tin and lead, completely encloses the laminations 2 and windings l and extends over the copper tubing II of leads I0.

- In addition metal I2 is disposed between the tube II in the air gap of the stator and strips 1 and solders the ends 9 of tube 8 securely within the mouth of the slot 3 in which the ends are located.

In constructing the stator I of the invention,

' after laminations 2 have been stacked together the windings l are located in slots 3, and the slot sticks 6 are slipped into the mouth of th slots to hold the windings in place.

The strips 1 are slipped into the mouth of the slots on top of slot sticks 6 with the tinned surface thereof to the outside of the respective slots.

Thereafter, the thiri sheet or tube 8 is rolled into or otherwise provided in the air gap of stator I and the ends thereof are turned or depressed into one of the slots 3 to lock the tube to the stator laminations 2. The tube preferably extends longitudinally to a line slightly beyond the end coils 5 of the windings 4.

The leads III are surrounded with copper tubing II and the stator I is then disposed within a vertically disposed collapsible jig comprising a mold I3 formed of four parts and supported within the cylinder It on the cap or plate I5 which closes the bottom of the cylinder. A cy- "lindrical tapered bar It extends upwardly within metal I2 from adhering thereto in the casting operation.

is located adjacent the windings while the strip I extends acros the open mouth of the slot. The exposed or outside face of the strip 1 is coated with a protective coating of. tin. l

A thin sheet or tube I of non-magnetic ma-' The poured non-magnetic metal II Whips mold I3.

When the stator I is placed in mold I3, the bar It extends through the center air gap thereof to provide a hollow bore in the cast metal I2.

After the stator is placed within the mold IS, the dowels II are inserted to space the stator from the mold in position for pouring of the metal I2. Dowels II permit complete circulation of metal between the mold and the stator and determine the thickness thereof.

The cylinder I4 and the mold are secured together by the set screws I8 which are threaded through the cylinder and into contact with The mold II with stator I confined therein is next placed in the oven I9 and the mold and stator are heated to from 275 to 300 F. The metal I2 which is in a molten state is then poured into the stator from a suitable source not shown through the upper open end 20 of the cylinder Id. The mold and stator are then allowed to cool until the metal I2 hardens.

The metal I! at the time of pouring has a temperature of approximately 380. In the pouring operation the metal i2 flows into all the vacant spaces between the stator i and the mold IS. The metal i2 completely covers the laminations 2, the end coils 5, and lead tubing ll adjacent the end coils. In addition the metal I! fills the spaces between the strips 1 and the tube 8 and solders the longitudinal ends 9 of tube I securely within the mouth of one o! the slots 3. The inner and outer ends of the tube I are also completely embedded in metal it.

After cooling, the set screws II are unthreaded, and the stator I with metal I: enveloping the same and mold II and mandrel it are removed from the cylinder ll. The parts of the mold II are separated from the outside oi! the molded stator and the mandrel It is removed from the inside of the stator. The outer surface of the poured stator is then finished to proper dimensions on the outside and is tinned, and then is bored out on the inside to the tube 8.

The metal I! hermetically seals the various parts of the stator I against entry of oil or moisture thereto. The windings I are securely held against movement by metal l2 and cannot pulsate by change of frequency or other shocks to which the stator may be subjected.

The invention is applicable to any electromagnetic apparatus employing laminations and windings where it is desirable to seal oil? the same from oil, moisture, or the like.

Various embodiments of the invention may be employed within the scope of the accomparwing claims,

I claim:

1. A metal cast dynamo electric element comprising a plurality of laminations stacked together and provided with longitudinally extending slots opening into the air gap thereof, electric windings disposed in said slots and having end coils extending from each end of the laminations. a non-magnetic strip closing the mouth of each slot, a thin non-magnetic sheet disposed adjacent the strips in the air gap and extending longitudinally along the air gap, and generally soit non-magnetic metal cast to completely surround said laminations. end coils and windings and to solder said thin metal sheet to the metal strips located in the mouth of the stator slots.

2. A metal cast dynamo electric element comprising a plurality of laminations stacked together and provided with longitudinally extending slots opening into the air gap thereof, a non-magnetic strip closing the mouth 0! each slot electric winding disposed in said slots and having end coils extending from each end of the laminations. a fluid resistant formed sheet of extremely thin non-magnetic material disposed in said air gap with the longitudinal ends thereof turned into one 0! said slots, and generally soit non-magnetic metal cast to completely surround said laminations, end coils and windings and to join the sheet at the longitudinal seam and to the laminations and windings within the stator air gap.

MARION B. SAWYER. 8a.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain Mar. 19, 1937 Number Number 

